The insurgents had seized a couple of strategic areas in western Aleppo after launching an offensive on October 28 in an attempt to break the siege imposed in July on rebel-held eastern Aleppo, which has also been targeted by waves of Syrian and Russian airstrikes.

Russia said last month that it would halt the airstrikes on the city and urged insurgents to leave. Despite the warnings, the fighters, including members of the al-Qa'ida-linked Fatah al-Sham Front, refused to leave after the government opened corridors for them to cross to Idlib, an insurgent stronghold.

The Britain-based Syrian Observatory for Human Rights said on Saturday that government forces and their allies have regained control of Al-Assad and Minyan districts, west of Aleppo.

"The epic battle for Aleppo has failed," said the Observatory's chief Rami Abdurrahman, using the term that the insurgents had assigned to the offensive.

Men walk past a tarpaulin and damaged buses erected as protection from snipers in the rebel held area of Old Aleppo. REUTERS/Abdalrhman Ismail

Syrian state media reported the two districts as retaken. State TV reported live from Minyan, which appeared firmly under government control.

"We fought them in every street, house, neighbourhood and schools, and they used mosques to launch attacks," an army brigadier general in Minyan told Al-Manar TV. The network is run by the Lebanese militant group Hezbollah, which is fighting alongside the forces of Syrian President Bashar al-Assad.

The Observatory said the fierce fighting left 508 dead. It said the dead insurgents included 90 foreign fighters while on the government side, 83 troops, 28 Hezbollah fighters and 41 other soldiers from Iran and Iraq were killed as well.

On Thursday, Jan Egeland, the special adviser to the UN envoy for Syria, said the last food rations in besieged eastern Aleppo will run out by next week. Speaking in Geneva, Mr Egeland said the last time the more than 250,000 people inside east Aleppo received any humanitarian aid was in the beginning of July.

Russia's military is willing to consider a new humanitarian pause for Aleppo if UN officials confirm their readiness to deliver aid and evacuate wounded and sick civilians.

Defence Ministry spokesman Majoe General Igor Konashenkov said on Saturday that such aid had been blocked by the insurgents during previous pauses in the fighting, which "showed that assurances of UN representatives about 'preliminary' agreements with militants in Aleppo are just words".

The capture of Minyan and Al-Assad came a day after the Russian military and a main Syrian opposition group traded allegations that the Syrian military or rebels used chemical weapons in Aleppo.